Turkish Journal of Hematology Volume: 35 - Issue: 1

Aydınok Y, et al: A National Registry of Thalassemia in Turkey
Turk J Hematol 2018;35:12-18
Demographic Characteristics of Patients
This was a relatively young cohort (51% male), of which 72%
of individuals were below 20 years old (Figure 1). A total of
378 subjects (19%) in the cohort were of preschool age (<6
years). The majority of subjects aged ≥6 years were students
(n=981, 67%). A total of 480 subjects (33%) were not attending
school. Just over half of these (n=256, 53%) were >18 years
old and employed, whereas 224 (47%) were unemployed and
214 of those were >18 years old. Of the unemployed patients
57% had only completed the 8-year primary education, whereas
33% had graduated from high school and 10% from university.
The schooling or employment status was not obtained from 149
subjects. All patients, except for 1%, were covered by social
security regardless of their social status.
Consanguineous marriage was reported for 48% of parents
and 51% of those were first-cousin marriages. Consanguineous
marriages accounted for 75% of parents from Şanlıurfa, which
was the city with the third highest number of thalassemic
patients on the registry. In comparison, consanguineous
marriages were reported in 38.5% and 29% of parents from
İstanbul and İzmir, respectively. Furthermore, the average
number of children born to parents with an affected child was
4 in Şanlıurfa but 2 in İstanbul and İzmir. A total of 214 families
in the registry had more than one thalassemic child.
Disease Characteristics
The majority of subjects (95%) had homozygous β-thalassemia
(Table 2). A total of 1385 β-thalassemia alleles reported from
724 patients contained 22 different β-thalassemia mutations.
The most common 11 mutations represented 90% of all
β-thalassemia alleles. IVS1-110(G->A) was the most prevalent
mutation (Table 3).
Although β-thalassemia intermedia (TI) was reported in 215
(11.5%) of 1873 patients with β-thalassemia, only one-third
of subjects (33.3%) were entirely transfusion-free. Regular
(>8 times/year), frequent (5-8 times/year), and occasional
(0-4 times/year) transfusions were reported in 79 (37.6%), 30
(14.3%), and 31 (14.8%) patients, respectively.
Splenectomy had been performed in 79 (38%) of 207 patients
with TI and 590 (37%) of 1594 patients with β-thalassemia
major (TM). The patients were divided into four age cohorts by
decades and splenectomy indication during the first decade was
compared between age cohorts II, III, and IV. The splenectomy
frequency in age cohort III displayed a slight decrease compared
to cohort IV and simply shifted to the second decade. However,
the frequency of splenectomy did not change in age cohort II
compared to III (Table 4).
A total of 115 patients with TM were aged <2 years at the time
of registration and had not met the criteria for starting ICT.
A total of 150 patients with TI, hemoglobin H (HbH) disease,
Table 2. The diagnosis of registered patients.
Diagnosis n %
β-thalassemia major 1658 83.4
β-thalassemia intermedia 215 10.8
β/S-thalassemia 16 0.8
S/S disease 77 3.9
HbH disease 22 1.1
HbH: hemoglobin H
Table 3. The most common β-thalassemia mutations in the
cohort.
β T mutation
Homozygous
Compound
heterozygous
Total
β T allele
IVSI-110(G->A) 234 184 652 47.1
IVSI-1(G->A) 26 53 105 7.6
IVSI-6(T->C) 24 56 104 7.5
Codon 39(C->T) 22 35 79 5.7
IVSII-745(C->G) 19 40 78 5.6
IVSII-1(G->A) 20 36 76 5.5
Codon 8(-AA) 23 26 72 5.2
Codon 44(-C) 17 11 45 3.3
Codon 5(-CT) 12 17 41 3.0
-30 (T->A) 10 13 33 2.4
IVSI-5(G->C) 10 9 29 2.1
%
Table 4. Changes in frequency and age of splenectomy in age cohorts by decades.
Age cohorts of patients
Age of
I (0-10 years), II (10-20 years), III (20-30 years), IV (30-40 years),
splenectomy (years)
n=685 (%)
n=716 (%)
n=366 (%)
n=129 (%)
0-10 37 (5.5) 135 (19) 73 (20) 33 (26)
10-20 - 105 (15) 137 (37) 36 (29)
20-30 - - 22 (6) 18 (15)
30-40 - - - 2 (1.5)
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